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On certain distinguished unitary representations supported on null cones
- American Journal of Mathematics
- Johns Hopkins University Press
- Volume 120, Number 5, October 1998
- pp. 1059-1076
- 10.1353/ajm.1998.0043
- Article
- Additional Information
Let [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01i" /] = [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="02i" /] or [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="03i" /], and let G = U(p, q; [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="04i" /]) be the isometry group of a [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="05i" /]-hermitian form of signature (p, q). For 2n ≤ min (p, q), we consider the action of G on Vn, the direct sum of n copies of the standard module V = [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="06i" /], and the associated action of G on the regular part of the null cone, denoted by X00. We show that there is a commuting set of G-invariant differential operators acting on the space of C∞ functions on X00 which transform according to a distinguished GL(n, [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="07i" /]) character, and the resulting kernel is an irreducible unitary representation of G. Our result can be interpreted as providing a geometric construction of the theta lift of the characters from the group G' = U(n, n) or O* (4n). The construction and approach here follow a previous work of Zhu and Huang [Representation Theory1 (1997)] where the group concerned is G = O(p, q) with p + q even.